Apparatus for determining the hardness of subsurface formations



June 6,1939. J. c. KARCHER APPARATUS FOR DETERMINING THE HARDNESS OF SUBSURFA CE FORMATIONS Filed April 27, 1936 2 Sheets-Sheet l JCEZFCfiRJ INVENTOR.

ATTORNEY.

June 6, 1939. c A H R 2,161,256

APPARATUS FOR DETERMINING THE HARDNESS OF SUBSURFACE FORMATIONS Filed April 27, 1936 2 Sheets-Sheet 2 INVENTOR.

ATTORNEY.

' aha/fez UNITED s'm'r asv PATENT OFFICE 'APPARATUS FOR DETERMINING THE HARD- NESS F SUBSURFACE FORMATIONS John C. Karcher. Dallas, Tex., assignor to Geophysical Service, Inc., Dallas, Tex., a corporation of New Jersey Application April 27, 1936. Serial No. 76,582

' 3 Claims. (CI. 13-51) This invention relates to apparatus for eX- section of drill stem. The lower end of the bot-- ploring bore holes as drilling proceeds, and it has tom section of drill stem is threadably connected particular reference to apparatus for determining to a, conventional type of rotary bit. These units the hardness of formations encountered by theare well known to those skilled in the art, and

5 drill bit of a rotary drilling machine. are not illustrated in the drawings. The upper 5 v The principal object of the invention is to proend of the shaft I is comprised of an integrally vide an apparatus whereby the relative hardness formed box 4 into which is screwed a convenof formations encountered during the drilling optional water swivel 5. eration may be observed and permanently re- A-cylindrical housing 6 is mounted concentri- 10 corded as drilling proceeds. cally on the shaft I, and is supported thereon by 10 With the foregoing object as paramount the the bearings I thereby enabling the shaft I to invention has particular reference to its salient. -rotate while the housing 6 stands still. features of construction and arrangement of A'plurality of permanent magnetsli are rigidly parts, to becomemanifest as the description promounted within the housing -Ii. Opposite the ceeds, taken in connection-with the accompanying 'poles of the magnets 8, armatures 9 are posi l5 drawings in which tioned, which carry electric coils III. Interposed Figure 1 is an elevational view of the preferred between the magnets-8 and th armatures 9 and embodiment of the invention, with portions of the spaced apart therefrom, a copper disc II is posihousing broken away. 1 tioned and is coaxially and rigidly attached to Figure 2 is an elevational viewof the invention the shaft I, thereby constraining the disc II to 20 shown attached to attendent parts of the drillrotate with the shaft 'I. The coils III are coning c ne, nected in'series by wires I2, and are further con- Figure 3 is a diagrammatic view of the wiring nected to a pair of binding posts I3. arrangement and appurtenances, Referring now to Figure 3, I4 denotes an am- Figure 4'is a modified form of the invention plifier-rectifier, which is connected to the bind? 25 shown in Figure 1, ing posts l3 by wires I5. An indicating meter I6 Figure 5 is a view on the line 5-5 on Figure 4, and a recording meter I! are connected by wires and I8 to the amplifier-rectifier I4 as shown;

Figure 6 is a further modified form of a device The operation of the device is as follows: When embodying the invention. the drill pipe, and consequently the shaft I is 30 Heretofore the operator of a rotary drilling turning at a uniform rate, there will be no change machine has had to rely upon his observations in the magnetic flux between the magnets 8 and of the general behavior of the drilling equ pment the armatures 9, consequently 'no current willbe as a means of determining the hardness of forgenerated in the coils III. -If, however, there is a mations in whichthe machine is'drilling at any chattering or vibration of the drill bit, this 5 given time. Determination by such a method is motion will betransmitted to-the shaft I, and acvery indefinite and often results in erroneom cordingly to the disc II. This will cause the disc conclusions as to the kind of formation in which II to have an'irregular rotational motion. This the bit is working. I f irregular rotational motion will cause changes in 40 The present 'invention provides instrumental the amount of flux passing from the magnets 8. 40 means for observing\and recording the variations to the armatures 9, and consequently will induce in behavior of the drilling machine as drilling a current in the coils I0. This'induced current proceeds through the various formations, and. passing through the amplifier-rect fier I4, will thereby provides means for determin'ng the varicause the indicating meter I6 and the recording ation in the kind of formation in such a way that meter IT to be actuated, and a consequent deflec- 45 the observations are independent of the judgment tion of the indicating elements of these meters. of the operator of the machine; Another embodiment of theinventicn is illus-' Continuing with a more detailed description of trated in Figures 4 and 5, wherein I9 is a hollow the drawings, reference is primarily made to shaft corresponding to the shaft l illustrated in Figure 1 in which I denotes a shaft having a Figures land 2. A cylindrical housing 20, corre- 5o central passage 2 therethrough. The lower end sponding to the housing 6 previously described is of the shaft I is threadably connected" to a gr'ef concentrically mounted upon the shaft I9 through stem 3 of a conventional rotary drilling mathe medium of bearings such as illustrated in chine. The lower end of the grief stem 3 is Figure 1.. A ring 2! isrigidly attached to the threadably connectedtothe upper end of the top shaft Hi, from which armature supports 22 are 55 connected to the ring 2! by hinges 2i, and are held in position by springs 28, which latter are connected to'the rotating ring 26 through a pair of radial arms 29. Thus it will be seen that the magnets 26, while constrained to rotate with the shaft i9, are free to vibrate when there is a' chattering of. the drill pipe. A pair of slip rings 30- are rigidly mounted upon the shaft i9, and are insulated therefrom.

One of the coils 24 is by insulating rings 3|. electrically connected to one of the slip rings 30, and the other coil is similarly connected to the companion slip ring. A brush 32 bears against one of the slip rings 30, and a companion brush 33 likewise-makes electrical contact with its corresponding slip ring. The brushes 32 and 33 are electrically connected to the binding posts 34 and 35 respectively through the medium of the hinged arms 36 and 31 and the wires 38 and 39, thebrushes 32 and 33 being held in contact with theirrespective slip ring by means of springs 40, which are attached to the arms 36 and v3!. It will be noted that the arms 36 and 3'! and the springs 40 are insulated from the housing 20. Wires 4| serve to connect the device to an. amplifier-rectifier, such as illustrated in Figure 3, which in turn is connected to a suitable indicating meter and recording meter.- The latter in"- struments will be actuated, due to an induced current, whenever there is a chattering of the drill pipe resulting from the encountering 'of a hard formation by the drill bit. .(1

A further embodiment of the invention-is illustrated in Figure 6, in which 42 denotes a hollow shaft corresponding-to the shafts i and [9, previously described. The shaft 42 has rigidly at tached thereto a ring 43, to which are attached a pair of radial arms 44. Slip rings 45 and 45 are disposed on eitherside of the ring 43 and are insulated from the shaft 42, .as illustrated in the modification shown in Figure 5.

A brush 31, attached to a pivoted and conducting arm 48 bears against the'slip ring 46, and a similar brush 49, attached to anarm50, has electricalcontact with the lower 'slip ring 45,-the brushes being held in contact with their respective slip-rings by means of springs 5|. Wires-52 serve to electrically connect them 48 and with the terminals 53' and 54.

A microphone s5 is suitably attached to the arm 44 and insulated therefrom, and-a similar microphone 55 is attached to the 44. ,A

weight 51 is attached to the. diaphragm act the microphone 55, and a similar weight-58 is attached to the diaphragm b of the-microphone 56.

fl'he microphones 55 and I are electrically;

. connected in series by a wire 53, the weight 51 being connected to the slip ring 45 by a wire" 53 and the weight 53 connected-to the slip ring 45 byawireil.

7 A wire serves the terminal.

with a 83, which in turn isconnected to the terminal'il the 64. of a transformer by wires "and". The secondaryof the transformer is'connected-to a pair of terminals 68, which are operatively connected to an amplifier-rectifl The latter in turn is coni i nected to the meters as previously described.

During the time of drilling in a hard formation,-

the chattering of the drill assembly will cause vibration of the weights 5'7 and 58 and a consequent change in the electrical resistance of the circuit, due to the increasing and decreasing pressure exerted upon the diaphragms a and This results in an induced voltage inthe secondary 61 of the transformer, and a consequent change in readings on the indicating and recording meters.

It has been foundthat when a drill bit is drilling in soft shale or clay there will be little or no vibration, and particularly torsional vibration in the drill stem. As a consequence the indicating meter will read substantially zero, since little or no current is generated in the modifications of the invention shown in Figures 1 and 4, and the current flow is substantially a constant in the variation of the invention illustrated in Figure 6.

If, however, the bit is drilling in a hard formation the tendency of the bit will be to grind and chatter, thus causing large torsional vibrations to progress up the drill pipe which will be transmitted to the copper disc II, illustrated in Figure- 1. Likewise, these vibrations result in vibrations of the'magnets 26, illustrated in Figure 4- and vibrations of the weights 51 and 58, shown in- Figure 6. These changes in current strength, after amplification and rectification, will cause the indicating meter to show considerable voltage. This voltage-becomes an indication that the bit is drilling in a hard formation.

. Manifestly the apparatus herein disclosed is capable of considerable modification, and such modification as is considered within the scope of trically conducting coil and a permanent magnet adjacently arranged and positioned near the periphery of said disc, and a similarly arranged coil and permanent magnet positioned on the opposite side of said-disc.

Apparatus for determining the variation in hardness of earth formations encountered by a rotary. bit while drilling, said apparatus including a conducting disc rigidly'and co-axially attached to the drill stem, stationary magnetic elements mounted on opposite sides of said disc and symmetrically arranged with reference to the plane of thedisc, and electrically conducting coils statipnarily disposedadjacent to said magneticelements.

3- Apparatps for determining the variation in 1 hardness of earth formations encountered by a rotary bit while drilling, said apparatus including a conducting disc rigidly and co-axially attached to the drill stem and arranged to rotate between "the poles of one or more magnets stationarily around the periphery of said disc at spaced intervals and electrically conducting coils "stationarily disposed adjacent to said poles of said magnets.

. JOHN C. KARCHER. 

